The main exception is a recent crossover study in T2D, where a strongly acidified sourdough bread and a functional low-sugar, low-GI bread both reduced 0–240 min interstitial-glucose AUC and peak insulin compared with a conventional yeast bread, suggesting that in metabolically compromised individuals—and when formulation is explicitly optimized for low GI—the “fermented bread” concept can translate into potentially clinically relevant glycemic improvements, albeit based on small, short-term studies [36,140,193,194]. Here, INS is linked to type 2 diabetes mellitus.